This invention relates to an apparatus, system and method for combining together images taken by camera devices placed at a plurality of locations to generate for display a synthesized or composite image. More particularly, the invention relates to a surveillance camera system and a surveillance camera image display method.
A surveillance work by means of a surveillance system using monitor cameras generally includes performing image acquisition by use of at least one or more surveillance cameras capable of capturing a portion or the entirety of an area under surveillance, and also includes displaying the captured scene images on a video image display device such as a cathode ray tube (CRT) that is installed at a remote location where a security officer or “surveillant” is present by simultaneously displaying multiple monitor camera-captured images at divided screen portions or alternatively by sequentially displaying the monitor camera images so that a selected one of them is displayed at a time while switching it to another, to thereby recognize and judge the occurrence of a critical event such as an unusual situation happened within the surveillance area. In such the surveillance work through observation of the monitor camera images, the human being who is a surveillant uses three kinds of information items—i.e., i) the imaging condition as to the surveillance area of interest that is being captured or “photographed” from which camera position at what view angle for which range of the area, ii) the captured image information per se, and iii) known information concerning the monitor camera'installation location—to make a comprehensive judgment for understanding and recognizing the event that presently happens in the surveillance area.
To do this, known surveillance systems are typically designed to employ a method for displaying on a video display device the three kinds of information—namely, the surveillance camera's imaging conditions, captured images, and known information as to the surveillance locations—while dividing the display screen into portions for respective visualization or a method for representing the information on a surveillance area as a map and for diagrammatically showing on the map the imaging conditions by use of symbols while letting the video image of a selected camera be displayed in a separate window (for example, see JP-A-6-284330, JP-A-2003-134503, JP-A-2002-77889, and JP-A-2002-344929).
In addition, there is known a technique for use in a surveillance system for airports, rivers, harbors or the like with relatively less obstructions within a range under surveillance. This technique uses a plurality of cameras with different picture angles to provide multiple captured scene images of a wide surveillance area, for reconstructing such images into a single image being viewed from a certain point and then synthesizing the entire surveillance area into a map being looked at from its overhead direction (see JP-A-2001-319218).
With the above-noted related arts, each is designed to display a camera-captured scene image in its native or “raw” form. For this reason, even when indicating with the aid of symbols the imaging conditions such as the imaging direction of a surveillance camera on a map indicative of the surveillance range, the surveillant is still required to carry out a series of recognition processes because of the lack of the matching or consistency in geometric relationship between the captured images and the map, which processes may include attempting to imagine or “re-image” the map-indicated surveillance range into a visual appearance of the monitor range in the case of looking at from the same view point as the monitor camera, comparing such the image to the actually captured surveillance image, and then recognizing an event that presently occurs within the surveillance range. Thus the surveillant is compelled to keep high concentration power constantly. This would cause problems, such as a risk that he or she is likely to commit judgment mistakes.
In addition, in cases where an increased number of obstructions such as public buildings or else are present in the surveillance range, the inconsistency or mismatch in geometric relationship between the surveillance camera-captured image and the map information can sometimes take place in a way depending upon the conversion processing to be performed during visual reconstruction into a single image.
Additionally, in the case of such mismatch of the geometric relationship between images captured by a plurality of cameras from different positions, the above-identified Japanese patent documents fail to provide any feasible solutions thereto.